Hydraulic clamps are commonly used in manufacturing operations to hold and clamp parts to stationary fixtures so that the parts may be machined or otherwise worked upon. Hydraulic clamps typically include a housing adapted for attachment to a fixture, a piston telescopically received within the housing for movement between a clamped position and a released position when hydraulic fluid is supplied to the housing, and a clamping lever or head attached to the distal end of the piston for holding and clamping the part to the fixture when the piston is shifted to its clamped position. Typically, several such clamps are mounted to a single fixture so that a part can be securely held from several sides while it is worked upon.
Many different types of hydraulic clamps exist, and the types are typically categorized by the motion of the clamping levers. One common type is a link clamp, which has a clamping lever that pivots down when its piston is moved to its extended, clamped position and pivots up and out of the way when the piston is moved to its retracted, released position. Link clamps accommodate hard-to-reach or hard-to-hit clamping points and are preferred over swing clamps and other types of clamps when it is desired to reach over a part to clamp it, rather than swing around it.
Conventional link clamps are designed for holding parts directly in front of the clamps and therefore must be equipped with offset clamping levers to hold parts that are offset from the front of the clamps. Unfortunately, offset levers induce high eccentric loading and therefore necessitate a lower clamp pressure to prevent damage to the clamps. Offset levers also twist, bend, or otherwise distort while clamping, resulting in uneven clamping forces.
Adjustable link clamps have been developed to permit clamping in different positions with respect to the clamp housing, but known versions of these adjustable clamps suffer from various limitations that limit their utility.